That's not the point. There are three different business models at work here:
Apple make consumer electronic products. Theuy
buy advertising to promote their core business of selling those products (that's exactly what you've just said). The services they offer (music, video etc.) are primarily designed to sell iPhones, iPads and watches.
Google sell advertising and customer data. The - mostly free - services they offer to consumers are primarily designed to gather that data and deliver that advertising. Their hardware products are primarily designed to promote their services.
Amazon are a retailer selling everything from aardvark husbandry supplies to zombie costumes. Their computing products are primarily designed to promote and sell Amazon retail products (and are often heavily subsidised loss-leaders).
(Microsoft - as far as I can tell - have a business model based on the Sirius Cybernetics Corporation from
The Hitchhiker's Guide to the Galaxy in which their most profitable division is the complaints department. Their products seem mainly designed to annoy people for no obvious benefit to either the customer or the company. Share and Enjoy

)
...now, yes, there is some convergence here: both Amazon and Apple are moving in on Google's turf to some extent, and both Amazon and Google have been tentatively seeing if they can get double-bubble by selling their ad delivery systems at premium prices and
still coin it in from ads and data gathering... but they're still clearly coming from three different directions.